The present disclosure relates to an image forming apparatus provided with a developing device of a touchdown developing method, using a two-component developer containing toner and carriers.
An electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile machine is configured to form a toner image on an image carrier by supplying a developer onto an electrostatic latent image formed on the image carrier (e.g. a photosensitive drum or a transfer belt), and developing the electrostatic latent image. As one of the developing methods, there is known a touchdown developing method of using a two-component developer containing toner as a non-magnetic material and carriers as a magnetic material. In this method, a layer of a two-component developer (a magnetic brush layer) is carried on a magnetic roller, a toner layer is carried on a developing roller (a toner carrier) by receiving toner from the magnetic brush layer, and toner is supplied from the toner layer onto an image carrier, whereby the electrostatic latent image is developed.